This invention relates to polycyclic dyes, especially 3,7-diphenyl benzodifuranone dyes.
EP-A-0363034 discloses the preparation of 3,7-diphenyl benzodifuranone dyes and EP-A-0469723 discloses the use of such dyes in thermal transfer printing. The dyes disclosed in EP-A-0363034 have the general formula. 
wherein
W is xe2x80x94NR1R2 or xe2x80x94OR3 
R3 is H or an optionally substituted alkyl, alkenyl, cycloalkyl or aralkyl group;
each of R1 and R2 independently is H, or an optionally substituted alkyl, alkenyl, cycloalkyl, aralkyl or aryl group; or
R1 and R2 together with the nitrogen atom to which they are attached form a heterocyclic ring; or
R1 or R2 together with the nitrogen atom and the adjacent carbon atom of Ring B form a heterocyclic ring;
Ring A is unsaturated or is substituted by from one to three groups
Ring B is unsubstituted, apart from the group W, or is substituted by one or two further groups;
each of Z1 and Z2 independently is xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94 or xe2x80x94NYxe2x80x94 in which Y is H, an optionally-substituted hydrocarbon group or an acyl group; and
each of X1 and X2, independently, is hydrogen, halogen, cyano, alkyl, aryl, carbamoyl, sulphamoyl, COOH and carboxylic acid esters.
One of the many groups additional to the group W which may be substituted on the Ring B is a hydroxyalkyloxy group.
EP-A-0492893 discloses a mixture of dyes each of the formula 
wherein
each of R1 and R2 independently is hydrogen, nitro, halogen, C1-6-alkyl, C1-6-alkoxy, phenyl, phenoxy, C1-6-alkoxyphenyl, cyano, xe2x80x94COOR and xe2x80x94SR, hydroxy, OCO.C1-6-alkyl, xe2x80x94SO2OH, xe2x80x94SO2Cl, xe2x80x94SO2C1-6-alkyl, xe2x80x94NR2 and xe2x80x94CONR2, xe2x80x94OC1-6-alkyl-COOR5, xe2x80x94OC1-6-alkylOR5, xe2x80x94OC1-6-alkylOR5OR5, and xe2x80x94OC1-6-alkylOCOR5, xe2x80x94OC2-6-alkenyl, xe2x80x94OC1-6alkyl-Z, xe2x80x94OC1-6-alkylOC1-6alkyl-Z and xe2x80x94OC1-6-alkylSC1-6-alkyl-Z in which Z is a 5-, 6- or 7-membered saturated or unsaturated heterocyclic residue; and
each of R3, R4, R5 and R6, independently, is hydrogen, C1-6-alkyl, halogen and C1-6-alkoxy,
in which each R independently is xe2x80x94H, C1-6-alkyl or phenyl and
in which each R5 independently is H, C1-6-alkyl, xe2x80x94C1-6-alkyl-C1-6-alkoxy or phenyl except where the mixture contains one compound of Formula (XI) in which R2 is xe2x80x94OC2H5 and R1, R3, R4, R5 and R6 are all absent, one compound of Formula (XI) in which R2 is n-propoxy and R1, R3, R4, R5 and R6 are all absent and 4-[1-cyano-methyl-4,5-dicyano imidaz-2-ylazo] N-ethyl-N-(ethoxycarbonyl-propyl)amino-benzene.
EP-A-0371223 discloses a range of 3,7-diphenyl benzodifuranone dyes of the formula 
wherein
each of A and B, independently, is hydrogen, a C1-C4 alkyl group or a C1-C4 alkoxy group;
Y is hydrogen, a C1-C4 alkyl group, a C1-C4 alkoxy group or a group of the formula xe2x80x94Oxe2x80x94R2xe2x80x94Xxe2x80x94R1,
or Y and B are taken together with each other to form a methylenedioxy group;
R1 is a C1-C4 alkyl group, a phenyl group or a C3 or C4 alkenyl group; R2 is an ethylene group unsubstituted or substituted by a methyl, methoxymethyl or ethoxymethyl group, a propylene group unsubstituted or substituted by a hydroxy, C1-C4 alkylcarbonyloxy or methyl group, or a C4-C8 alkylene group unsubstituted or substituted by a hydroxy, C1-C4 alkylcarbonyloxy or C1-C4 alkoxy group; and
X is a divalent group of xe2x80x94Oxe2x80x94,xe2x80x94Sxe2x80x94,xe2x80x94SOxe2x80x94,xe2x80x94SO2xe2x80x94 or xe2x80x94N(R3)xe2x80x94 in which R3 is a hydrogen atom or a C1-C4 alkyl group;
with the proviso that when X is a divalent group of xe2x80x94Oxe2x80x94 or xe2x80x94Sxe2x80x94 and Y and B are not taken together with each other to form a methylenedioxy group, and when R2 is an unsubstituted ethylene or unsubstituted propylene group, R1 is a C3 or C4 alkyl or alkenyl group, or a C1-C4 alkyl group, respectively. In such dyes, the group xe2x80x94Oxe2x80x94R2xe2x80x94Xxe2x80x94R1 may be an alkoxyalkoxy group.
Surprisingly, we find that 3,7-diphenyl benzodifuranone dyes having a hydroxyalkoxy group at the 4-position of at least one of the 3- and 7-phenyl groups show improved levelling properties as compared with the corresponding dyes containing a 4-alkoxy groups and improved build up as compared with the corresponding dyes containing a 4-hydroxy group.
Thus, the present invention provides a polycyclic dye of the formula (I) 
wherein
each of R1, R2, R4 and R5, independently, is hydrogen, alkyl or alkoxy;
R3 is hydrogen, alkyl, optionally substituted alkoxy or amino; and
Y is a straight or branched C1-8 alkylene group.
The alkyl group or the alkyl moiety of the alkoxy group of each of R1-R5 is preferably a C1-6 alkyl, more preferably a C1-4 alkyl group or moiety. A C1-4 alkyl group or moiety can be straight-chained or branched and be for example methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec.butyl or tert.-butyl.
Preferably, ih the formula (I),
each of R2, R4 and R5 is hydrogen;
R1 is hydrogen, methyl or ethyl;
R3 is hydrogen, alkyl or alkoxy; and
Y is a straight or branched C2-5 alkylene group.
Especially preferred 3,7-diphenyl benzodifuranone dyes have the respective formulae (Ia), (Ib) and (Ic) 
In another preferred range of dyes within the formula (I), R3 is a substituted alkoxy group
(a) of the formula xe2x80x94OR6CO2R7OR8, wherein each of R6, R7 and R8 independently is a straight or branched C1-6 alkylene group; or
(b) of the formula xe2x80x94OR9OH, wherein R9 is a straight or branched C1-8 alkylene group; or
(c) wherein the substituent is a tetrahydrofurfuryl or tetrahydropyran-2-ylmethyl group, an especially preferred substituted alkoxy group being the fur-2-ylmethoxy group.
A 3,7-diphenyl benzodifuranone dye of the formula (I), defined above, may be prepared, in accordance with a process aspect of the invention, by a process which comprises reacting a compound of the formula 
wherein
each of R3, R4 and R5 is as defined above, with a mandelic acid derivative of the formula 
xe2x80x83wherein
A is hydroxyl, (C1-4 alkyl) carbonyloxy or halogen;
B is hydrogen, C1-4 alkyl or aryl;
R10 is a C1-4 alkyl or phenyl group; and
each of R1, R2 and Y is as defined above to form a 2,6-dioxo-2,3,6,7-tetrahydro benzodifuranone derivative (IV) oxidising the derivative (IV) to obtain the corresponding 2,6-dioxo-2,3-dihydrobenzodifuranone derivative (V) and deacylating the derivative (V) to provide the polycyclic dye of the formula (I).
Halogen is preferably fluorine, chlorine or bromine. Aryl is preferably phenyl or substituted phenyl.
Especially preferably, in the formula (III), A is hydroxyl, B is hydrogen and R10 is methyl.
The reaction of the compound of the formula (II) with the mandelic acid derivative of the formula (III) is preferably carried out in the presence of an acid catalyst, e.g. sulphuric acid, p-toluene sulphonic acid or dodecylbenzene sulphonic acid, and preferably at a temperature of from 50 to 70xc2x0 C. and preferably for a period of from 3 to 5 hours.
The oxidation reaction is preferably carried out at a temperature of from 40 to 60xc2x0 C. and preferably from a period of from 15 to 45 minutes. Especially preferred oxidising agents are chloranil, hydrogen peroxide and ammonium persulphate.
The deacylation treatment is preferably carried out at a temperature of from 80 to 100xc2x0 C. and preferably for a period of from 2 hour to 2 hours, and more preferably in a polar solvent such as 2-ethoxyethanol or dimethyl formamide. An especially preferred deacylating agent is hydrochloric or sulphuric acid.
An alternative process for preparing a polycyclic dye of the formula (I), given and defined above, comprises reacting a compound of the formula 
wherein
each of R1, R2, R3, R4 and R5 is as defined above; with an alkylating agent of the formula 
xe2x80x83wherein
Y is as defined in above;
R10 is a C1-4 alkyl or phenyl group; and
X is a halogen atom;
to obtain an acyl-2,6-dioxo-2,3,6,7-tetrahydrobenzodifuran derivative of the formula 
xe2x80x83wherein
each of R1, R2, R3, R4, R5, R10 and Y is as defined above; and deacylating the derivative (VIII) to provide the polycyclic dye of the formula (I).
Preferably, in the formula (VII), X is bromine and R10 is methyl.
Typically, the alkylating agent may be 2-bromoethyl acetate, 4-bromobutyl acetate or 5-bromopentyl acetate.
The alkylation reaction is preferably carried out in the presence of a solvent, for example, toluene, sulpholane or dimethyl formamide, and more preferably under reflux for, say, 2-5 hours.
The alkylation reaction is also preferably carried out in the presence of a base, for example, calcium or potassium carbonate or dicylohexylamine.
The deacylation of the compound (VIII) may be carried out in a manner analogous to that described above for deacylation of compound (V) and is again preferably carried out at a temperature of from 80 to 100xc2x0 C. and preferably for a period of from 2 hour to 2 hours, and more preferably is a polar solvent such as 2-ethoxyethanol or dimethyl formamide. An especially preferred deacylating agent is hydrochloric or sulphuric acid.
In yet another alternative, but less preferred process, the hydroxyphenyl compound of the formula (VI) may be reacted directly with a haloalkanol of the formula
Xxe2x80x94Yxe2x80x94OH
wherein each of X and Y is as defined above, for example, 2-bromo-ethanol, 4-bromobutanol, 5-bromopentanol, 3-chloropropanol or 6-chlorohexanol, to obtain the compound of the formula (I).
The hydroxyphenyl compound of the formula (VI) may be prepared by a known method such as that described in EP-A-0033583 (see Example 26).
According to a further feature of the present invention, there is provided a process for colouring a fibre material on blend thereof, especially a synthetic textile material or fibre blend thereof, which comprises applying thereto a polycyclic dye as hereinbefore defined.
The synthetic textile material may be selected from secondary cellulose acetate, cellulose triacetate, polyamide, polyacrylonitrile and aromatic polyester. The synthetic textile material is preferably polyamide such as polyhexamethylene adipamide or aromatic polyester, especially polyethylene terephthalate. Fibre blends may comprise mixtures of different synthetic textile materials or mixtures of synthetic and natural textile materials. Preferred fibre blends include those of polyester cellulose, such as polyester-cotton, and polyester-elastane (xe2x80x9celastanexe2x80x9d is a polyurethane/polyether block copolymer, commercially available as xe2x80x9cLycraxe2x80x9d). The textile materials or blends thereof may be in the form of filaments, loose fibres, yarn or knitted fabrics.
The dyes according to the invention, optionally in conjunction with other disperse dyes, may be applied to the synthetic textile materials or fibre blends thereof by processes which are conventionally employed in applying disperse dyes to such materials and fibre blends.
Suitable process conditions include the following:
i) exhaust dyeing at a pH of from 4 to 6.5, at a temperature of from 125xc2x0 C. to 140xc2x0 C. for from 10 to 120 minutes under pressure of from 1 to 2 bar, a sequestrant optionally being added;
ii) continuous dyeing at a pH of from 4 to 6.5, at a temperature of from 190xc2x0 C. to 225xc2x0 C. for from 15 seconds to 5 minutes, a migration inhibitor optionally being added;
iii) printing direct at a pH of from 4 to 6.5, at a temperature of from 160xc2x0 C. to 185xc2x0 C. for from 4 to 15 minutes for high temperature steaming, or at a temperature of from 190xc2x0 C. to 225xc2x0 C. for from 15 seconds to 5 minutes for bake fixation with dry heat or at a temperature of from 120xc2x0 C. to 140xc2x0 C. and 1 to 2 bar for 10 to 45 minutes for pressure steaming, wetting agents and thickeners (such as alginates) of from 5 to 100% by weight of the dye optionally being added;
iv) discharge printing (by padding the dye on to the textile material, drying and overprinting) at a pH of from 4 to 6.5, migration inhibitors and thickeners optionally being added;
v) carrier dyeing at a pH of from 4 to 6.5, at a temperature of from 95xc2x0 C. to 100xc2x0 C. using a carrier such as methylnaphthalene, diphenylamine or 2-phenylphenol, sequestrants optionally being added.
In all the above processes, the dyes according to the invention is applied as a dispersion comprising from 0.01% to 4% by weight of the dye mixture in aqueous medium.
Compositions comprising dispersions of the disperse dye of the invention or an aqueous medium form a further feature of the present invention. The compositions may comprise from 1% to 35%, typically from 5% to 30%, by weight of a mixture of the dyes in an aqueous medium. The compositions are preferably buffered at pH 2 to 7, more preferably at pH 4 to 6.
The dye dispersions may further comprise ingredients conventionally used in colouration applications such as dispersing agents, for example lignosulphonates, naphthalene sulphonic acid/formaldehyde condensates or phenol/cresol/sulphanilic acid/formaldehyde condensates, surfactants, wetting agents such as alkyl aryl ethoxylates which may be sulphanated or phosphated, inorganic salts, de-foamers such as mineral oil or nonanol, organic liquids and buffers. Dispersing agents may be present at from 10% to 200% on the weight of the dye. Wetting agents may be used at from 0% to 20% on the weight of the dye. The dispersions may be prepared by bead milling the dye with glass beads or sand in an aqueous medium or by combining dispersions of milled dyes.
Dispersions may be dried, after the addition of any extra dispersing agents, to give a solid physical form with from 5 to 60% by weight of total colour.
In addition to the above-mentioned application processes, the dyes of the invention may be applied to synthetic textile materials and fibre blends by ink-jet printing, the substrates optionally having been pre-treated to aid printing. For ink-jet applications, the application medium may comprise water and a water-soluble organic solvent, preferably in a weight ratio of 1:99 to 99:1, more preferably 1:95 to 50:50 and especially in the range 10:90 to 40:60. The water-soluble organic solvent preferably comprises a C1-C4-alkanol, especially methanol or ethanol, a ketone, especially acetone, methyl ethyl ketone, 2-pyrrolidone or N-methylpyrrolidone, a glycol, especially ethylene glycol, propylene glycol, trimethylene glycol, butane-2,3-diol, thiodiglycol or diethylene glycol, a glycol ether or diethylene glycol monomethyl ether, urea, a sulphone, especially bis-(2-hydroxyethyl) sulphone or mixtures thereof.
The dye may also be applied to textile materials using supercritical fluid solvents, for example supercritical carbon dioxide, in which case the dye formulating agents may optionally be omitted.